Right-side cardiac output determined with a newly developed catheter-tip resistivity probe using saline indicator.

Right-heart cardiac output was determined in 10 dogs using a newly developed, highly accurate catheter-tip resistivity probe. A saline indicator was injected into the right atrium and the blood resistivity was monitored at the catheter tip in the pulmonary artery. The resulting dilution curves were calibrated electrically according to the manner in which blood resistivity changes with saline concentration and cardiac output values were calculated. Cardiac output values determined simultaneously by the direct Fick method were used as a reference.